But I got the error "'CImportLog::CImportLog' : constructors not allowed a return type". So, where am I supposed to put the struct? Also, if I declare it in one class, will I be able to use it in my other class (.cpp) files?

...of the constructor declaration in the class definition I presume. Or, was that the semicolon at the end of the class definition? I always forget that one too, so I always type the closing brace with a semicolon BEFORE typing in the members and functions.